This relates to underwater pool cleaners of the type adapted to travel in random paths along the underwater surfaces of a swimming pool to pick up debris and to sweep minute particles therefrom.
Floating debris, such as leaves, twigs and the like are generally removed from residential and commercial swimming pools, by means of skimmers or openings at water level, which draw in and collect matter floating on the surface of the pool. Foreign matter suspended in the water, such as fine particles of soil, are separated out at a pool water filtration system conveniently located near the swimming pool. A main filter pump draws water from the surface skimmer, and from the bottom of the pool, to pass it through the filtration unit and then recirculate it back to the swimming pool.
While the skimmer removes much of the floating matter, and the filtration system removes a considerable amount of the fine matter in suspension, the systems together are generally incapable of maintaining a swimming pool sufficiently clean and clear for an extended period. As a result, periodic cleaning of the underwater surfaces by other means is generally required in order to maintain a satisfactory level of water cleanliness and clarity.
Commonly ued by pool owners and pool service contractors are various types of vacuum heads that are connected to the return line to the main pump and then attached to the end of a pole for movement by pushing and pulling the head along the underwater surfaces of the pool. While many pool owners would prefer to avoid the chore of so cleaning the pool manually, they also prefer to avoid the expense of employing a pool service company to do this on a regular and continuing basis. Accordingly, in recent years, swimming pool cleaning devices which operate automatically, have enjoyed increasing popularity.
For example, a pool cleaning device of the type disclosed in U.S. Pat. No. 3,032,044 has a buoyant body, which is connected by a flexible hose to the pool water circulation pump or to a booster pump. A horizontal nozzle propels the body along the surface of the pool, pulling sweep hoses, through which jets of water are issued, whereby the water jets, as well as the sweeping action of the hoses themselves, dislodge fine sediment from the pool surfaces to be suspended in the water and thereafter separated by the pool filtration system.
More recently, there have been developed a number of underwater pool cleaning devices for removal of larger particles and debris directly from the underwater surfaces of the pool. An example of such devices is shown in U.S. Pat. No. 3,822,754 and related U.S. Pat. Nos. 3,936,899 and 3,972,339. In these devices, a carriage moves along the bottom and side walls, collecting debris by means of a vacuum, the carriage being propelled by drive wheels. The drive wheels are, in turn, driven by a turbine against which a stream of water is directed. A more recent drive system of this general type is shown in U.S. Pat. No. 4,558,479.
While underwater pool vacuuming devices of the type described in these patents have proven very effective in dislodging and collecting leaves and other relatively large forms of debris, some problems have been encountered in jamming and even damaging the exposed drive trains. Moreover, booster pumps are generally required to deliver enough water under pressure to both drive the vehicle and produce enough vacuum to effectively sweep the underwater surfaces.